﻿/*
 * Copyright 2001,2004-2005 The Apache Software Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * This package is based on the work done by Keiron Liddle), Aftex Software
 * <keiron@aftexsw.com> to whom the Ant project is very grateful for his
 * great code.
 */

namespace SharpCompress.Compressor.BZip2
{
    /**
      * A simple class the hold and calculate the CRC for sanity checking
      * of the data.
      *
      * @author <a href="mailto:keiron@aftexsw.com">Keiron Liddle</a>
      */

    internal class CRC
    {
        public static int[] crc32Table =
            {
                unchecked((int) 0x00000000), unchecked((int) 0x04c11db7), unchecked((int) 0x09823b6e),
                unchecked((int) 0x0d4326d9),
                unchecked((int) 0x130476dc), unchecked((int) 0x17c56b6b), unchecked((int) 0x1a864db2),
                unchecked((int) 0x1e475005),
                unchecked((int) 0x2608edb8), unchecked((int) 0x22c9f00f), unchecked((int) 0x2f8ad6d6),
                unchecked((int) 0x2b4bcb61),
                unchecked((int) 0x350c9b64), unchecked((int) 0x31cd86d3), unchecked((int) 0x3c8ea00a),
                unchecked((int) 0x384fbdbd),
                unchecked((int) 0x4c11db70), unchecked((int) 0x48d0c6c7), unchecked((int) 0x4593e01e),
                unchecked((int) 0x4152fda9),
                unchecked((int) 0x5f15adac), unchecked((int) 0x5bd4b01b), unchecked((int) 0x569796c2),
                unchecked((int) 0x52568b75),
                unchecked((int) 0x6a1936c8), unchecked((int) 0x6ed82b7f), unchecked((int) 0x639b0da6),
                unchecked((int) 0x675a1011),
                unchecked((int) 0x791d4014), unchecked((int) 0x7ddc5da3), unchecked((int) 0x709f7b7a),
                unchecked((int) 0x745e66cd),
                unchecked((int) 0x9823b6e0), unchecked((int) 0x9ce2ab57), unchecked((int) 0x91a18d8e),
                unchecked((int) 0x95609039),
                unchecked((int) 0x8b27c03c), unchecked((int) 0x8fe6dd8b), unchecked((int) 0x82a5fb52),
                unchecked((int) 0x8664e6e5),
                unchecked((int) 0xbe2b5b58), unchecked((int) 0xbaea46ef), unchecked((int) 0xb7a96036),
                unchecked((int) 0xb3687d81),
                unchecked((int) 0xad2f2d84), unchecked((int) 0xa9ee3033), unchecked((int) 0xa4ad16ea),
                unchecked((int) 0xa06c0b5d),
                unchecked((int) 0xd4326d90), unchecked((int) 0xd0f37027), unchecked((int) 0xddb056fe),
                unchecked((int) 0xd9714b49),
                unchecked((int) 0xc7361b4c), unchecked((int) 0xc3f706fb), unchecked((int) 0xceb42022),
                unchecked((int) 0xca753d95),
                unchecked((int) 0xf23a8028), unchecked((int) 0xf6fb9d9f), unchecked((int) 0xfbb8bb46),
                unchecked((int) 0xff79a6f1),
                unchecked((int) 0xe13ef6f4), unchecked((int) 0xe5ffeb43), unchecked((int) 0xe8bccd9a),
                unchecked((int) 0xec7dd02d),
                unchecked((int) 0x34867077), unchecked((int) 0x30476dc0), unchecked((int) 0x3d044b19),
                unchecked((int) 0x39c556ae),
                unchecked((int) 0x278206ab), unchecked((int) 0x23431b1c), unchecked((int) 0x2e003dc5),
                unchecked((int) 0x2ac12072),
                unchecked((int) 0x128e9dcf), unchecked((int) 0x164f8078), unchecked((int) 0x1b0ca6a1),
                unchecked((int) 0x1fcdbb16),
                unchecked((int) 0x018aeb13), unchecked((int) 0x054bf6a4), unchecked((int) 0x0808d07d),
                unchecked((int) 0x0cc9cdca),
                unchecked((int) 0x7897ab07), unchecked((int) 0x7c56b6b0), unchecked((int) 0x71159069),
                unchecked((int) 0x75d48dde),
                unchecked((int) 0x6b93dddb), unchecked((int) 0x6f52c06c), unchecked((int) 0x6211e6b5),
                unchecked((int) 0x66d0fb02),
                unchecked((int) 0x5e9f46bf), unchecked((int) 0x5a5e5b08), unchecked((int) 0x571d7dd1),
                unchecked((int) 0x53dc6066),
                unchecked((int) 0x4d9b3063), unchecked((int) 0x495a2dd4), unchecked((int) 0x44190b0d),
                unchecked((int) 0x40d816ba),
                unchecked((int) 0xaca5c697), unchecked((int) 0xa864db20), unchecked((int) 0xa527fdf9),
                unchecked((int) 0xa1e6e04e),
                unchecked((int) 0xbfa1b04b), unchecked((int) 0xbb60adfc), unchecked((int) 0xb6238b25),
                unchecked((int) 0xb2e29692),
                unchecked((int) 0x8aad2b2f), unchecked((int) 0x8e6c3698), unchecked((int) 0x832f1041),
                unchecked((int) 0x87ee0df6),
                unchecked((int) 0x99a95df3), unchecked((int) 0x9d684044), unchecked((int) 0x902b669d),
                unchecked((int) 0x94ea7b2a),
                unchecked((int) 0xe0b41de7), unchecked((int) 0xe4750050), unchecked((int) 0xe9362689),
                unchecked((int) 0xedf73b3e),
                unchecked((int) 0xf3b06b3b), unchecked((int) 0xf771768c), unchecked((int) 0xfa325055),
                unchecked((int) 0xfef34de2),
                unchecked((int) 0xc6bcf05f), unchecked((int) 0xc27dede8), unchecked((int) 0xcf3ecb31),
                unchecked((int) 0xcbffd686),
                unchecked((int) 0xd5b88683), unchecked((int) 0xd1799b34), unchecked((int) 0xdc3abded),
                unchecked((int) 0xd8fba05a),
                unchecked((int) 0x690ce0ee), unchecked((int) 0x6dcdfd59), unchecked((int) 0x608edb80),
                unchecked((int) 0x644fc637),
                unchecked((int) 0x7a089632), unchecked((int) 0x7ec98b85), unchecked((int) 0x738aad5c),
                unchecked((int) 0x774bb0eb),
                unchecked((int) 0x4f040d56), unchecked((int) 0x4bc510e1), unchecked((int) 0x46863638),
                unchecked((int) 0x42472b8f),
                unchecked((int) 0x5c007b8a), unchecked((int) 0x58c1663d), unchecked((int) 0x558240e4),
                unchecked((int) 0x51435d53),
                unchecked((int) 0x251d3b9e), unchecked((int) 0x21dc2629), unchecked((int) 0x2c9f00f0),
                unchecked((int) 0x285e1d47),
                unchecked((int) 0x36194d42), unchecked((int) 0x32d850f5), unchecked((int) 0x3f9b762c),
                unchecked((int) 0x3b5a6b9b),
                unchecked((int) 0x0315d626), unchecked((int) 0x07d4cb91), unchecked((int) 0x0a97ed48),
                unchecked((int) 0x0e56f0ff),
                unchecked((int) 0x1011a0fa), unchecked((int) 0x14d0bd4d), unchecked((int) 0x19939b94),
                unchecked((int) 0x1d528623),
                unchecked((int) 0xf12f560e), unchecked((int) 0xf5ee4bb9), unchecked((int) 0xf8ad6d60),
                unchecked((int) 0xfc6c70d7),
                unchecked((int) 0xe22b20d2), unchecked((int) 0xe6ea3d65), unchecked((int) 0xeba91bbc),
                unchecked((int) 0xef68060b),
                unchecked((int) 0xd727bbb6), unchecked((int) 0xd3e6a601), unchecked((int) 0xdea580d8),
                unchecked((int) 0xda649d6f),
                unchecked((int) 0xc423cd6a), unchecked((int) 0xc0e2d0dd), unchecked((int) 0xcda1f604),
                unchecked((int) 0xc960ebb3),
                unchecked((int) 0xbd3e8d7e), unchecked((int) 0xb9ff90c9), unchecked((int) 0xb4bcb610),
                unchecked((int) 0xb07daba7),
                unchecked((int) 0xae3afba2), unchecked((int) 0xaafbe615), unchecked((int) 0xa7b8c0cc),
                unchecked((int) 0xa379dd7b),
                unchecked((int) 0x9b3660c6), unchecked((int) 0x9ff77d71), unchecked((int) 0x92b45ba8),
                unchecked((int) 0x9675461f),
                unchecked((int) 0x8832161a), unchecked((int) 0x8cf30bad), unchecked((int) 0x81b02d74),
                unchecked((int) 0x857130c3),
                unchecked((int) 0x5d8a9099), unchecked((int) 0x594b8d2e), unchecked((int) 0x5408abf7),
                unchecked((int) 0x50c9b640),
                unchecked((int) 0x4e8ee645), unchecked((int) 0x4a4ffbf2), unchecked((int) 0x470cdd2b),
                unchecked((int) 0x43cdc09c),
                unchecked((int) 0x7b827d21), unchecked((int) 0x7f436096), unchecked((int) 0x7200464f),
                unchecked((int) 0x76c15bf8),
                unchecked((int) 0x68860bfd), unchecked((int) 0x6c47164a), unchecked((int) 0x61043093),
                unchecked((int) 0x65c52d24),
                unchecked((int) 0x119b4be9), unchecked((int) 0x155a565e), unchecked((int) 0x18197087),
                unchecked((int) 0x1cd86d30),
                unchecked((int) 0x029f3d35), unchecked((int) 0x065e2082), unchecked((int) 0x0b1d065b),
                unchecked((int) 0x0fdc1bec),
                unchecked((int) 0x3793a651), unchecked((int) 0x3352bbe6), unchecked((int) 0x3e119d3f),
                unchecked((int) 0x3ad08088),
                unchecked((int) 0x2497d08d), unchecked((int) 0x2056cd3a), unchecked((int) 0x2d15ebe3),
                unchecked((int) 0x29d4f654),
                unchecked((int) 0xc5a92679), unchecked((int) 0xc1683bce), unchecked((int) 0xcc2b1d17),
                unchecked((int) 0xc8ea00a0),
                unchecked((int) 0xd6ad50a5), unchecked((int) 0xd26c4d12), unchecked((int) 0xdf2f6bcb),
                unchecked((int) 0xdbee767c),
                unchecked((int) 0xe3a1cbc1), unchecked((int) 0xe760d676), unchecked((int) 0xea23f0af),
                unchecked((int) 0xeee2ed18),
                unchecked((int) 0xf0a5bd1d), unchecked((int) 0xf464a0aa), unchecked((int) 0xf9278673),
                unchecked((int) 0xfde69bc4),
                unchecked((int) 0x89b8fd09), unchecked((int) 0x8d79e0be), unchecked((int) 0x803ac667),
                unchecked((int) 0x84fbdbd0),
                unchecked((int) 0x9abc8bd5), unchecked((int) 0x9e7d9662), unchecked((int) 0x933eb0bb),
                unchecked((int) 0x97ffad0c),
                unchecked((int) 0xafb010b1), unchecked((int) 0xab710d06), unchecked((int) 0xa6322bdf),
                unchecked((int) 0xa2f33668),
                unchecked((int) 0xbcb4666d), unchecked((int) 0xb8757bda), unchecked((int) 0xb5365d03),
                unchecked((int) 0xb1f740b4)
            };

        public CRC()
        {
            InitialiseCRC();
        }

        internal void InitialiseCRC()
        {
            globalCrc = unchecked((int) 0xffffffff);
        }

        internal int GetFinalCRC()
        {
            return ~globalCrc;
        }

        internal int GetGlobalCRC()
        {
            return globalCrc;
        }

        internal void SetGlobalCRC(int newCrc)
        {
            globalCrc = newCrc;
        }

        internal void UpdateCRC(int inCh)
        {
            int temp = (globalCrc >> 24) ^ inCh;
            if (temp < 0)
            {
                temp = 256 + temp;
            }
            globalCrc = (globalCrc << 8) ^ CRC.crc32Table[temp];
        }

        internal int globalCrc;
    }
}